Rapid growth in both animal and plant systems is accompanied by an increase in the levels of polyamines and, in some cases, histamine; included in these physiological conditions of growth are, e.g., neoplastic growth, human pregnancy, and seed germination. These conditions often exhibit in addition greatly enhanced, transient levels of diamine oxidase (histaminase) activity. In cancerous growth, for example, it has also been shown that agents counteracting the neoplasm decrease these polyamine levels. However, little or no work has been done on the enzymatic systems performing the same function. We wish to initiate this work at the basic level of elucidating the structure-function relationships in the amine-amine oxidase systems of plant and animal sources and the general mechanism of action of these enzymes. Also, the basis of substrate inhibition and its possible role in the regulation of amine catabolism will be investigated. Studies of the enzymatic activity toward these polyamines on the subsequent effects on the DNA with which they are normally associated will lend additional information concerning the role of diamine oxidase in these rapid growth situations. The details of the enzymatic catalysis and the bases of substrate specificity and inhibitions will be determined via dynamic magnetic resonance probe studies. These studies will make a significant contribution to the elucidation of the function of both the amines and their oxidation enzymes in rapidly developing tissue.